Re: [Monotone-devel] How to get the newest cert beginning with a certain substring?

[Christof Petig]

Nathaniel Smith schrieb:
> On Wed, Feb 02, 2005 at 10:24:41AM +0100, Christof Petig wrote:
>
> > Now to start an update I need to ask for
> > - the latest (using the date) cert and revision for a given
> > host+repository+module.
> > (- Perhaps every cert and revision matching the given module)
>
>
> I think the answer is that you don't want to use the date cert.  You
> want to use the ordering imposed by ancestry.

You are right. Ordering them by (revision) date was a (perhaps possible)
optimization (which was easily adoptable by sql).

> The model is similar to 'heads' -- 'heads' finds revisions that have a
> given branch cert, that have no descendents that have that same branch
> cert.  s/branch/cvs_revision/ and you have exactly what you want to do
> here.

Since I actually decided to ignore the branch (this way you can import
new parts of a branch into a different branch without needing the
(already existing) branch point in the dest branch) I tend to parse each
and every cvs-revision tag in the database (ouch).

> > This brings me to another question: This cert is highly compressible and
> > also changes not much between revisions. This brings this cert near to
> > file characteristics. Is it planned to reference files (or any other
> > diff+gzip stored entity) from certs (I know this opens a can of worms
> > when it comes to synchronization)? Perhaps not, but once this topic
> > comes up a second or third time, I would suggest to implement it.
>
>
> It's tricky, since cert values need to be SELECT'ed on (at least,
> branch cert values do), and IIUC gzipped data is not necessarily
> normalized.  Random idea - store the information in a .mt file in the
> filesystem?  Then a cert could be used to say "this revision has an
> up-to-date .mt-cvs", and nothing else.  Could actually use .mt-attr
> for this, though at some risk of annoying people by cluttering it
> up with stuff they shouldn't touch...

Problems:
- I might need multiple tree states for different repositories (yes,
that's sick, but I might actually need it to sync between two different
CVS repositories)
- There's no way to add such an internal file to an already existing
revision
- You get all kinds of bad things like conflicts merging this file,
people trying to edit it, people commiting revisions with this file in it

[For now I did not gzip the cert because monotone-viz does not
understand gzipped certs (II-guess-C)] and it's nice to see its contents
displayed.

   Christof

PS: Your sanity checks really slow cvs_pull down, I currently import a
1985 edge (revisions) repository into a test database and its at #792
after 138:21 cpu minutes (on a 3GHz high end machine). Looks like I will
provide a "--relaxed" switch in my branch to speed my tests up (to a
bearable speed). Burn test your CPUs with monotone :-( ... ;-)
PPS: cvs_pull is already capable of a full (HEAD branch) remote import.

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